[PATCH v2] ARM: realview: basic device tree implementation
nicolas.pitre at linaro.org
Thu May 22 11:39:20 PDT 2014
On Thu, 22 May 2014, Arnd Bergmann wrote:
> On Thursday 22 May 2014 14:09:52 Nicolas Pitre wrote:
> > On Thu, 22 May 2014, Arnd Bergmann wrote:
> > > On Thursday 22 May 2014 15:45:03 Catalin Marinas wrote:
> > > > By making the DMA memory Strongly Ordered, we avoid the
> > > > L220 write buffer. In addition to the above commit, we also had
> > > > 2503a5ecd86c (ARM: 6201/1: RealView: Do not use outer_sync() on
> > > > ARM11MPCore boards with L220).
> > >
> > > Ah, so this also stands in the way of multiplatform realview
> > Isn't the real value of a multiplatform realview in the ability to use
> > it with Qemu? Did Qemu go to the extreme of emulating all those cache
> > issues?
> The qemu developers have in the past always argued strongly that they
> want to run the same kernel that runs on real hardware. Having a kernel
> that runs only on the emulated version but not on actual hardware is
> clearly against that goal, and we should use CONFIG_ARCH_VIRT for
> that purpose.
But the kernel that actually runs on the real hardware also runs on Qemu
already. It is just that, by some coincidence, a multi-platform kernel
that pretends to have the same peripherals as a Realview board could
also be used on Qemu.
Otherwise I really don't see the point in making the code more complex
just to make a multi-platform kernel run on actual Realview hardware
that is quite obsolete now and that very few people have access to.
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